Loop stitch shuttle arrangement



United States Patent 198,201,202.168,181.187.232.233z242/1nquired [72] inventor Yasukata Eguchi [56] References Cited Tokyo, J p UNITED STATES PATENTS [211 P 811,074 20,686 6/1858 Johnson 112/201 [221 PM 27119769 514 653 2/1 894 l-ieberlin 112 v 168 Continuation-impart of Ser. No. 644,696, 687 5 1 H190! Ammerman 112/168 June 8, 1967, now Pat. No. 3,447,498 [45] Patented Nov. 17, 1970 Primary Examiner-H. Hampton Hunter [73] Assignee Janome Sewing Machine C0., Ltd. y Striker Tokyo, Japan [32] Priority June 9, 1966, July 11, 1966 [33] Japan [3 l] 41/316,801 and 41/4 1,791 ABSTRACT: A loop stitch shuttle is secured to a rotary hook member for rotation with the same, and has a peripheral cylindrical surface formed with a spiral shaped groove terminating [54] ARRANGEMENT at the free end of the shuttle. A loop formed by the rotary g hook is engaged by the spiral shaped groove of the shuttle be- [52] US. Cl......l 112/168, fore released by the rotary hook, and is held in spread condi- 1 12/201, 1 12/228 tion so that the needle can enter into the spread loop while the [51] int. Cl. D05b 1/14, same is transported toward the free end of the shuttle. After D0513 l/06 the rotary hook member again catches the needle thread to [50] Field of Search 1 12/197, form a new loop, the loop held by the shuttle passes over the v free end of the same and is released.

Patented Nov. 17, 1970 Sheet INVENTOR. Ms wan-4 E60! Patented Nov. 17, 1970 3,540,390

Sheet 2 of2 INVENTOR. jda umm scold/Z LOOP STITCH SHUTTLE ARRANGEMENT CROSS REFERENCE TO A RELATED APPLICATION The present application is a continuation-in-part application of the copending US. Pat. application Ser. No. 644,696 entitled LOOP STITCH SHUTTLE FOR SEWING MACHINES, now issued as US. Pat. No. 3,447,498, dated June 3, 1969.

BACKGROUND OF THE INVENTION In the copending US. Pat. application Ser. No. 644,696, a small loop stitch shuttle of complex configuration is secured to the rotary hook member of a sewing machine, and holds a thread loop released by the rotary hook member in a spread condition facilitating the entering of the needle into the loop released by the rotary hook. After the rotary hook member catches the next thread, the loop stitch shuttle releases the loop.

Loop stitches formed in this manner of a single thread are used for basting material in such a manner that the row of stitches can be easily ripped.

SUMMARY OF THE INVENTION It is one object of the invention to provide a loop stitch shuttle arrangement comprising a loop stitch shuttle having a very simple structure.

A related object of the invention is to provide a loop stitch shuttle which can be inexpensively manufactured, but operates completely reliably.

Another objectof the invention is to provide a loop stitch shuttle consisting of a cylindrical body.

Another object of the invention is to provide a loop stitch shuttle which is easily handled, and attached to or detached from the rotary hook member.

Another object of the invention is to provide a loop stitch shuttle with resilient arresting means so that the loop stitch shuttle is automatically attached to the rotary hook member when inserted into the same, and released from the hook member when withdrawn therefrom in axial direction.

Another object of the invention is to provide a loop stitch shuttle arrangement in which a loop held by the loop stitch shuttle is loosened before being released by the same, while at the same time the following loop is caught by the rotary hook member and expanded by the same.

Another object of the invention is to provide a loop stitch shuttle with a spiral shaped, preferably helical guide means for simultaneously holding a loop in a spread condition, and transporting the loop in axial direction until it passes over the end ofthe loop stitch shuttle.

With these objects in view, the present invention relates to a rotary loop stitch shuttle including a body having a peripheral surface of revolution formed with a spiral shaped guide means, such as a groove, for a thread loop, and having a free end at which the spiral shaped guide means terminates for releasing the loop during rotation of the shuttle; and attaching means at the other end of the body.

The loop stitch shuttle of the invention is used in a loop stitch arrangement provided in a sewing machine having a reciprocating needle.

A loop stitch arrangement according to the invention comprises a rotary hook member for catching a needle thread, forming a loop of the same, and releasing the loop in successive angular positions; and a loop stitch shuttle detachably connected to a bobbin mounting means of the rotary hook member, and having a free end and a spiral-shaped groove ending at the free end.

The spiral-shaped groove engages the loop formed by the rotary hook member during rotation of the same with the loop stitch shuttle, and holds the released loop in spread condition during movement of the needle into the spread loop. At the same time, the spread loop is transported by the spiral-shaped groove toward the free end so that the loop is released by the shuttle when passing over the free end of the same after the rotary hook member has again caught the needle thread to form a new loop.

In the preferred embodiment of the invention, the loop stitch shuttle has a peripheral surface of revolution formed with the spiral-shaped groove, and the free end of the shuttle has an end face, preferably formed with a cutout, in which the spiral-shaped groove terminates The hook member has a cavity in which the mounting means is located, and a wall bounding the cavity and having a central opening through which the shuttle projects out of the cavity so that the free end of the shuttle is located outside of the cavity. The surface of revolution and the spiral shaped groove are partly located within the cavity and partly located outside of the cavity so that the loop formed by the rotary hook slides on the wall until being engaged by the spiral shaped groove which holds the loop spread when released by the rotary hook member.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims.

The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary exploded perspective view illustrating a loop stitch shuttle arrangement according to the invention;

FIG. 2 is a vertical axial sectional view illustrating the loop stitch shuttle arrangement of FIG. 1;

FIG. 3 is a plan view of a loop stitch shuttle used in the arrangement of FIGS. land 2;

FIG. 4 is a side view, partially in vertical axial section, illustrating the loop stitch shuttle;

FIG. 5 is a front elevation of the loop stitch shuttle; and

FIG. 6 is a perspective front view of the loop stitch shuttle on a reduced scale.

DESCRIPTION OF THE PREFERRED EMBODIMENT The general arrangement of a sewing machine which may be provided with a loop stitch shuttle arrangement according to the invention, is described and illustrated in the copending application Ser. No. 644,696 in which it is explained how the needle forms loops which are caught by the rotary hook member which is provided with a loop stitch shuttle.

A rotary hook member 2 has an annular rib 24 with a slide surface ending in a hook 23. Coupling cutouts 25, 25', best seen in FIG. 2, are provided in the frustoconical rear wall 24a. The frustoconical front wall 24b has a central opening 24c for insertion and removal of the loop stitch shuttle l. The rotary hook member 2 is mounted in the shuttle holder 3 which has a race 31 providing a small clearance between the race 31 and the slide surface 24' which is slanted. In this manner, the rotary hook can easily be mounted in the holder 3, and smooth rotation is assured. Holder 3 has a central opening, and two bores 33 on opposite sides of the openings for the insertion of screws by which the holder 3 is secured to a supporting wall of the sewing machine bed, not shown.

Holder 3 has two retaining arms 32 which are turnably mounted on opposite sides of the holder and have an open position in which cap 4 can be inserted into a corresponding recess in holder 3, whereupon the arms 32 are turned to a position engaging the projecting studs 41 on cap 4 for securing the same. Cap 4 has a flat spring 42 secured to its periphery.

In the position in which holder 3 is closed by the cap 4, rotary hook member 2 is mounted for rotation about a central axis. A mounting pin 21 is located in the axis of the rotary hook member, and is secured to the central portion of wall 24a. The free end portion of mounting pin 21 has an annular arresting groove 22. Mounting pin 21 is used for mounting a bobbin thereon when the sewing machine is used for making regular stitches. However, since the sewing machine is to be used for making loop stitches of a single thread, the standard bobbin is removed, and the loop stitch shuttle 1 is mounted on mounting pin 21.

Loop stitch shuttle 1 has a cylindrical mounting portion with a central bore 12 receiving mounting pin 21. A radial slot 16 is formed in the mounting portion, and extends into the flange portion whose diameter is greater than the diameter of the mounting portion. Flange portion 10 has a cylindrical cavity 13 communicating with slot 16 and central bore 18, and the free end portion of mounting pin 21 is located in the cavity 13.

An arresting spring 14 is secured by a screw 15 to the mounting portion of the shuttle 1, and has a bent part abutting a shoulder 17 at the end of slot 167 An edge in leaf spring 14 projects into the annular arresting groove 22 of mounting pin 21 when loop stitch shuttle 1 is fully inserted into the hook member 2. The free end 19 of the arresting spring 14 is located in the cavity 13 which provides access to the arresting spring 14.

The larger flange 10 has a peripheral surface of revolution, shown to be cylindrical, formed with a spiral shaped helical groove 11. The position of flange 10 is such that part of it, and the corresponding part of the groove 11, is located within the cavity of the rotary hook member 2, while the other part of it projects through opening 24c so that the end of the spiral shaped groove 11 is located outside of the rotary hook member 2. The free end of flange portion 10 is circular, and formed with a segment-shaped recess 11', best seen in FIGS. 5 and 6. Segment shaped recess 11 is bounded by a straight shoulder 11a extending along a chord of the circular end face and being tangential to a circle whose diameter is smaller than the diameter of the end face 10. The spiral shaped groove 11 terminates in the recess 11'.

Since the end portion 20 of the arresting spring 14 projects into one of the cutouts 25, depending on the angular position in which loop stitch shuttle 1 was inserted into hook member 2, the loop stitch shuttle 1 cannot be angularly displaced or turned about mounting pin 12.

in the illustrated embodiment, the groove 11 is provided in a cylindrical peripheral surface, and is helical. However, ifit is considered necessary to vary the tension of a loop held in the spiralshaped groove 11, the depth of groove 11 may be partly varied, or the spiral-shaped groove provided on a frustoconical surface of revolution.

Before the sewing machine is used for a loop stitching operation, a bobbin case is removed from mounting pin 21, and the loop stitch shuttle 1 is inserted in axial direction through opening 240 into the cavity of hook member 1 so that mounting pin 21 enters the bore 12 and arresting spring 14 locks and arrests the shuttle l on mounting pin 21. End portion 20 of spring 14 assures a predetermined angular position of the recess 11 in the end face of shuttle 1, When hook member 2 is rotated with shuttle 1, hook 23 of hook member 2 catches the thread of the needle and forms a loop which is expanded during rotation of hook member 24. During one revolution, the expanded loop is released by hook 23, and

slides over wall 24b to a position held in the spiral-shaped groove of shuttle 1 which spreads the released loop and holds the same in a position in which the needle can enter into the spread loop. During rotation of shuttle l, the spread loop in groove 11 is transported by the same toward the free end of the shuttle, and after a certain time slides into recess 11 and is released by the shuttle.

in a sewing machine having a needle bar actuating mechanism including a crank, the expanded loop is held by shuttle 1 while the needle bar is once raised after the loop has been caught by the hook 23 of hook member 2 and again lowered until the needle is at least in the lower dead center position of its reciprocating movement. In order to preset the rotation angle of the drive shaft of the sewing machine to 0 when the needle bar is at its upper dead center position, the

loop is held by shuttle 1 while the drive shaft rotates from the angle 200 to the angle 480. which are 280 of rotation. However, in accordance with the present invention, the rotary hook member 2 performs two revolutions during each reciprocation of the needle bar, so that the loop is held by shuttle 1 during twice 280. which are 560 of the angle of rotation of the drive shaft, whereupon the loop is released by the free end of shuttle 1 at the forward end of the spiral-shaped groove 1 1.

In this condition, the next following thread loop is formed in the expanded preceding loop and caught by hook 23 of hook member 2.

By repetition of these operations, successive loop stitches are formed. Due to recess 11 in the front end face of shuttle l, the expanded preceding loop drops into recess 1! just be fore being released, the part of the loop on the side leading to the next following loop. In this manner, the tension of the expanded loop on shuttle l is reduced which has the effect of allowing free formation of the following loop. Due to this function of the shuttle l and recess [1, reliable formation ofa row of loop stitches or chain stitches is assured, and no loops are skipped. If the loop on the shuttle is twisted. the engaging relation between the same and the shuttle l is not detrimentally affected.

It will be understood that each of the elements described above, or two or more together, may also find a useful applica tion in other types of loop stitch arrangements differing from the types described above.

While the invention has been illustrated and described as embodied in a loop stitch shuttle having a peripheral helicalguide groove for spreading a loop released by a rotary hook member, and for releasing the loop after the rotary hook member has caught the thread again, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

lclaim:

1. In a sewing machine having a reciprocating needle, in combination, a loop stitch shuttle arrangement extending sub stantially transversely to the direction of needle movement comprising a rotary hook member for catching a needle thread, forming a loop of the same, and releasing the loop in successive angular positions, said rotary hook member having a bobbin mounting means; and a loop stitch shuttle detachably connected to said bobbin mounting means and having a free end and a peripheral surface of revolution including a spiral shaped groove extending around said surface and ending at said free end, said spiral shaped groove engaging the formed loop inwardly of said free end during rotation of said loop stitch shuttle with said rotary hook member and holding the released loop in spread condition during movement of said needle into the spread loop while transporting said spread loop toward said free end so that said loop is released by said shuttle when passing over said free end after said rotary hook member again catches the needle thread to form a new loop.

2. Loop stitch shuttle arrangement as claimed in claim 1 wherein said shuttle has a peripheral surface of revolution formed with said spiral shaped groove; and wherein said free end has an end face at which said spiral shaped groove terminates; and wherein said hook member has a cavity in which said mounting means is located, and a wall bounding said cavity and having a central opening through which said shuttle projects out of said cavity so that said free end is located outside of said cavity whereby said surface of revolution and said spiral shaped groove are partly located within said cavity and partly located outside of said cavity so that said loop sliding on said wall is engaged by said spiral shaped groove.

3. Loop stitch shuttle arrangement as claimed in claim 1 wherein said mounting means supports said shuttle for axial movement into and out of said rotary hook member; and wherein said shuttle includes means resiliently engaging said mounting means to attach said shuttle to said mounting means and hook member, and means engaging a part of said hook member for blocking rotation of said shuttle relative to said hook member.

4. Loop stitch shuttle arrangement as claimed in claim 1 wherein said bobbin mounting means includes a mounting pin secured to the center of said rotary hook member and having an arresting recess; wherein said loop stitch shuttle has at the end remote from said free end a bore for receiving said mounting pin, and includes an arresting spring resiliently engaging said arresting recess of said mounting pin for attaching said shuttle to said rotary hook member.

5. Loop stitch shuttle arrangement as claimed in claim 4 wherein said rotary hook member has at least one coupling cutout; and wherein said spring projects into said coupling cutout whereby rotation of said shuttle about said mounting pin is blocked.

6. Loop stitch shuttle arrangement as claimed in claim 1 wherein said free end of said shuttle has an end face formed with a cutout in which one end of said spiral shaped groove terminates.

7. Loop stitch shuttle arrangement as claimed in claim 1 wherein said shuttle has a mounting portion engaging said bobbin mounting means, and a cylindrical flange formed with said spiral shaped groove so that said groove is helical, said flange having a circular end face forming said free end; and wherein said end face if formed with a segment-shaped recess in which one end of said groove terminates.

8. Loop stitch shuttle arrangement as claimed in claim 7 wherein said segment-shaped recess is bounded by a straight shoulder extending along a chord of said circular end face and tangential to a circle whose diameter is smaller than the diameter of said helical groove.

9. Loop stitch shuttle arrangement as claimed in claim 1 wherein said mounting means includes a mounting pin secured at the center of said hook member and having an annular arresting recess; wherein said shuttle has a cylindrical mounting portion formed with a central bore receiving said mounting pin, and a cylindrical flange formed with said spiral shaped groove and having a cavity communicating with said bore, said cylindrical mounting portion being formed with a radial slot connected with said bore and said cavity; comprising an arresting leaf spring secured to said mounting portion and being located in said slot projecting into said cavity. and engaging said annular recess for resiliently holding said shuttle against axial movement away from said hook member; wherein said hook member has a cutout; and wherein said leaf spring has a coupling portion projecting into said cutout for blocking turning movement of said shuttle about said mounting pin.

10. A rotary loop stitch shuttle including a body having a peripheral surface of revolution formed with a spiral shaped guide means for a thread loop, said guide means including a groove extending about said peripheral surface, said body having a free end at which said spiral shaped guide means terminates for releasing the loop during rotation of said shuttle; and attaching means at the other end ofsaid body 

